168 research outputs found
Nonlinear sigma model approach for chiral fluctuations and symmetry breakdown in Nambu-Jona-Lasinio model
In this paper we discuss symmetry breakdown in NJL model at low N_c. In
particular we propose a modified NJL model that displays a symmetry breakdown
and also at finite temperatures under certain conditions the chiral
fluctuations in this model give rise to a phase analogous to pseudogap phase of
strong-coupling and low carrier density superconductors.Comment: accepted to Phys. Rev. D. Latest updates of this and related papers
are available at http://www.teorfys.uu.se/PEOPLE/egor
Rotational response of superconductors: magneto-rotational isomorphism and rotation-induced vortex lattice
The analysis of nonclassical rotational response of superfluids and
superconductors was performed by Onsager (in 1949) \cite{Onsager} and London
(in 1950) \cite{London} and crucially advanced by Feynman (in 1955)
\cite{Feynman}. It was established that, in thermodynamic limit, neutral
superfluids rotate by forming---without any threshold---a vortex lattice. In
contrast, the rotation of superconductors at angular frequency ---supported by uniform magnetic field
due to surface currents---is of the rigid-body type (London Law). Here we show
that, neglecting the centrifugal effects, the behavior of a rotating
superconductor is identical to that of a superconductor placed in a uniform
fictitious external magnetic filed . In particular,
the isomorphism immediately implies the existence of two critical rotational
frequencies in type-2 superconductors.Comment: replaced with published versio
Unusual mechanism of vortex viscosity generated by mixed normal modes in superconductors with broken time reversal symmetry
We show that under certain conditions multiband superconductors with broken
time-reversal symmetry have a new vortex viscosity-generating mechanism which
is different from that in conventional superconductors. It appears due to the
existence of mixed superfluid phase-density mode inside vortex core. This new
contribution is dominant near the time reversal symmetry breaking phase
transition. The results could be relevant for three band superconductor
.Comment: 7 pages, 2 figure
Domain walls and their experimental signatures in s+is superconductors
Arguments were recently advanced that hole-doped BaKFeAs
exhibits state at certain doping. Spontaneous breaking of time reversal
symmetry in state, dictates that it possess domain wall excitations.
Here, we discuss what are the experimentally detectable signatures of domain
walls in state. We find that in this state the domain walls can have
dipole-like magnetic signature (in contrast to the uniform magnetic signature
of domain walls superconductors). We propose experiments where
quench-induced domain walls can be stabilized by geometric barriers and be
observed via their magnetic signature or their influence on the magnetization
process, thereby providing an experimental tool to confirm state.Comment: Replaced with a version in print in Physical Review Letters; Minor
changes; 8 pages, 9 figure
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